Relatively large rotary drills may commonly be used in the mining industry for the drilling of holes in ore beds and strata. Large earth boring machines, commonly known as blast-hole drilling rigs may be used in a process which involves mapping out a drill pattern, drilling a blast hole, and filling the blast hole with explosives. An individual blast pattern may typically consist of 50 or more holes, each hole containing a measured quantity of explosives required to fracture the strata as intended.
FIG. 1 shows a typical blast-hole drilling rig (100), such as that described in U.S. Pat. No. 7,143,845. The drilling rig (100) includes a carriage (102), a mast (104) disposed on the carriage (102), and a rotary head (106) mounted on the mast (102), where the rotary head (106) rotates a drill string on which a drill bit is mounted. The rotary head may be raised up or lowered down the mast by, for example, a hydraulically driven feed system. The rotary head (106) includes a housing forming an internal chamber, a driving mechanism, and a rotation transmission mechanism disposed in the chamber, for rotating the drill pipe. The rotation transmission mechanism includes a gear system having a power input section operably connected to the motor, and a power output section adapted for connection to the drill pipe. The rotation transmission mechanism may include an anti-vibrational inertial body forming part of the power input section for storing rotational energy to even-out rotary speed variations and resist the generation of vibrations during operation. A cab (108) is typically attached to the carriage (102), and may include controls for operating the drill rig (e.g., programmable logic controllers, controller area network (CAN) based devices, etc.) for processing and displaying data obtained from sensors on the rotary head (106).
In addition, a blast-hole drilling rig (100) typically includes a tachometer (not shown) used to monitor the rotary speed of the drill pipe. A tachometer is an instrument capable of displaying revolutions per minute (RPMs). More specifically, the tachometer is located in the cab (108), and is wired to a pulse-pick up (PPU). The PPU, which is a type of sensor for measuring the RPMs of the drill pipe (not shown), is typically operatively connected to the rotary head (106) and measures the RPMs of a drill pipe that is drilled into the earth.
As the rotary head moves up and down the mast of the drill rig, the wiring between the pulse pick-up (PPU) and the tachometer located in the cab console must also travel with the rotary head. Thus, as the rotary head traverses the length of the mast, the wiring often fatigues through constant flexing and fails. Weather conditions also affect the failure rate of the wires. Increased longevity of the PPU wiring may be achieved by pulling the wiring through a hydraulic hose and anchoring this securely. However, even with this additional support, the wiring eventually fails due to fatigue. Due to the frequent failure of the wiring, drilling typically continues without such measurements, with the operator on the rig instead making visual observations about the RPM and rate of penetration.
However, as the industry moves toward autonomous (unmanned) drilling, there will be no human on board the drilling rig to observe drilling. Data wires for the radio tachometer would need to be more reliable because measurement and monitoring of such operating parameters are necessary for autonomous drilling control. Specifically, for autonomous drilling rigs, it is important that the automatic drilling control system be aware of all operating parameters such as how fast the drill pipe is turning.
What is needed is a more reliable and longer lasting method for transmission of data within a surface drill rig.